Thermal energy may be employed to ablate or otherwise treat tissue. The thermal energy may have a variety of forms, including radio frequency energy, microwave electromagnetic energy, laser energy, acoustic energy, or thermal conduction.
Radio frequency (RF) ablation may be used to treat patients with tissue anomalies. For example, cardiac ablation treatments involve the use of heat or freezing to create lesions in tissue to restore normal functioning of electrical activity near the tissue. Generally, cardiac ablation involves introducing a catheter into the heart where a therapeutic procedure can be carried out on abnormal heart tissue. RF ablation catheters employ electrodes at a distal end that can transfer RF or microwave electromagnetic energy to heart tissue. Catheter ablation may be used to treat atrial fibrillation and other types of heart rhythm disorders. RF ablation may also be used to treat other organs or tissue anomalies, such as cancer.
RF ablation devices generally direct electrical current from the active electrode on the catheter through the patient's body to a dispersive electrode that is externally attached to a location on the patient. The dispersive electrode, sometimes referred to as a neutral electrode, return electrode, or ground pad, provides a contact for RF signals to flow through the patient, where the current is dispersed to provide low current density through the dispersive electrode. The dispersive electrode may also provide a reference node for RF filters in the ablation system to reduce the effects of the RF energy on electrogram quality.